Health risk assessment of heavy metals in arid soils of the Nile Delta, Egypt using GIS and multivariate statistical analyses

Economic expansion has led to an increase in new toxins in the environment, creating a global problem for managing both environmental and human health. This study aimed to quantify the concentration of heavy metals (HMs) in soils of the Kafr El-Sheikh Governorate, located in the northern Nile Delta, Egypt, and to evaluate potential health risks by integrating Geographic Information Systems (GIS) with multivariate statistical analyses. Soil samples from 27 sites were analysed for potentially toxic elements (As, Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) using Inductively Coupled Plasma Mass Spectrometry. Soil pollution indices such as enrichment factor (EF), contamination factor (CF), and geoaccumulation index (Igeo) were assessed. In addition, non-carcinogenic and cancer risk indices were calculated. To identify the origins of HMs in the research area, Pearson's bivariate correlation, principal component, and hierarchical cluster analyses (PCA) were used. The findings revealed that the mean HM concentrations (mg kg-1) were in the following order: Fe (10706 ± 2855)>Mn (697.53 ± 138.46)> As(210.07 ± 20.23)> Zn (207.40 ± 216.76)>Ni(112.43 ± 13.68)> Cu (87.15 ± 47.69)> Pb(31.11 ± 8.66)> Co(23.97 ± 5.96)> Cd (6.50 ± 5.62). The EF, CF, and Igeo indices indicated that the soils in the study area were contaminated with metals. The risk index values indicated moderate, considerable, and very high ecological risk, with a median value of 2060.40 (range: 192.95-5006.97). From PCA results, the possible sources of the metals in the arid soils included pesticides and chemical fertilizers, except for Mn, which appeared to originate from geogenic sources. Both children and adults had hazard quotient and Hazard index values less than one in all three exposure pathways, except for As in the ingestion pathway for children.. Furthermore, the total cancer risk (sum of ingestion, inhalation, and dermal contact pathways for each element) associated with children's exposure to the elements under investigation was as follows: Pb (4.5E-02)> As (4.1E-03)> Ni (2.6E-03)> Cd (4.7E-05). Consequently, the largest cancer risk was determined to be from Pb. These results provide valuable information that emphasizes the need to mitigate pollution from potentially toxic elements in the Nile delta and minimize health concerns for the local population.